// Two cubes sharing a face.
// This is a non-manifold object since the collapsed vertices are not distinct.
polyhedron(
  points=[
    [0, 0, 0],
    [1, 0, 0],
    [0, 1, 0],
    [1, 1, 0],
    [0, 0, 1],
    [1, 0, 1],
    [0, 1, 1],
    [1, 1, 1],

    [2, 0, 0],
    [2, 1, 0],
    [2, 0, 1],
    [2, 1, 1],
  ],
  faces=[
    [6,7,5],[6,5,4],
    [0,1,3],[0,3,2],
    [4,5,1],[4,1,0],
    [5,7,3],[5,3,1],
    [7,6,2],[7,2,3],
    [4,0,2],[4,2,6],
    [7,11,10],[7,10,5],
    [1,8,9],[1,9,3],
    [5,10,8],[5,8,1],
    [10,11,9],[10,9,8],
    [11,7,3],[11,3,9],
    [5,1,3],[5,3,7],
  ]);
